1. Field of the Invention
The present invention relates to a medical instrument for an endoscope which is used by passing through the endoscope and a treatment method.
2. Description of Related Art
A procedure for removing a calculus may be performed as an endoscopic procedure. In this case, since a papillary area, which is an exit of a bile duct, is narrow, no calculus can be discharged as it is. Accordingly, the calculus is taken out after a tear sphincter is incised by a papillotome passing through an endoscope and the exit of the bile duct is then expanded.
For example, a conventional papillotome is disclosed in Japanese Patent Application, Publication No. 2004-275785. The papillotome passes a treatment channel of an endoscope and projects from a distal end of the endoscope. A distal portion of the papillotome is inserted into a bile duct through a papilla in accordance with torsion of an inserting portion of the endoscope, adjustment of curvedness, upward and downward movements of an erecting device, and advance and retreat operations of the papillotome itself. If necessary, a guide wire is inserted into a lumen of the papillotome. When a knife is stretched by operating a handy operating portion of the papillotome and radio-frequency current is applied thereto, a teat sphincter is incised and an exit of the bile duct is enlarged.
In the state in which the guide wire is left in the bile duct, only the papillotome is removed from the bile duct and the channel of the endoscope. Next, a basket or a balloon for collecting a calculus is inserted through the guide wire. The basket or the balloon is directed up to an upstream of the calculus along the guide wire. In the case of basket, the basket is opened by a hand-side operation. In the case of balloon, the balloon is supplied with air by a syringe from a hand side and thereby swollen. In this state, when the basket or the balloon is taken out toward the exit of the bile duct, the calculus is captured by the basket or the balloon and discharged together to the outside of the bile duct.
In this procedure, the papilla is incised by the papillotome such that an opening of the exit of the bile duct is enlarged. However, when an incision length is too short or the calculus is too large, the calculus is stuck in the exit of the bile duct and cannot be discharged. In this case, the calculus is collected by surgery, or endoscopically-collected by being destroyed with ESWL (extracorporeal shock wave lithotripsy) and thereby being reduced in size. Otherwise, the calculus is collected using the above-described basket or balloon by being endoscopically-destroyed and thereby being reduced in size.
In addition, when the papilla is largely incised by the papillotome, the calculus is easily extracted. However, when a blood vessel near the papilla is cut, bleeding is caused. In general, incision up to an upper edge of a projection on an entrance side of the papilla is referred to as large incision, two thirds of the incision is referred to as medium incision, and one third of the incision is referred to as small incision. Since a possibility of existence of a blood vessel more increases as nearer to the upper edge of the projection, a possibility of bleeding is higher in the medium incision than in the small incision and is higher in the large incision than in the medium incision. In general, an opening of about 5 mm is formed by the medium incision. Since the opening has a stretching property to some extent, a calculus having a size up to about 10 mm can be discharged. Today, the medium incision is mainly performed from the viewpoint of a risk of bleeding. The calculus having a size up to about 10 mm is collected without destruction, however, a calculus having a size more than 10 mm is collected using a complicated procedure, as described above.
As a method having a small risk of bleeding, there is a method of expanding the papilla by a dilation balloon having a withstand pressure instead of the incision with the papillotome.